Revista Internacional de Contaminación Ambiental
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Estudio concluyó que alimentos peruanos contienen altas concentraciones de metales normados y no normados
Get PDFEffect of hydraulic retention time on sulfide production with sludge from hydrothermal vent sediments and its utilization on the removal of Cu, Zn, and Al
No full textThe present work aimed to evaluate the production of sulfide through the application of different hydraulic retention times (HRT) and different sulfate loading rates in an up-flow anaerobic sludge blanket (UASB) reactor utilizing acetate-butyrate as electron donors and the coupling of the reactor to a crystallizer to remove metals. The sulfidogenic sludge for the UASB was generated from hydrothermal vent sediments and this was operated at room temperature (18-22 ºC). The sulfate reduction process was linked to the precipitation of Cu2+, Zn2+ and Al3+ in a crystallizer coupled to the UASB reactor (two-stage system) to avoid the toxicity of the metals to the sludge. The concentration of dissolved sulfide increased with the HRT up to 312.9 mg HS–/L at 3 d of HRT. As the sulfate loading rate was increasing, the maximum sulfide concentration obtained was of 376.8 mg HS–/L at 500 mg SO4–2/L/d (1500 mg/L), whereas the concentration of Cu2+, Zn2+ and Al3+ was up to 150, 100, and 100 mg/L, respectively. The removal efficiencies of Cu2+, Zn2+, and Al3+ were higher than 98% when they were fed separately. When a mixture of metals was added, the removal efficiency was close to 80%. Recovery of metals was lower than 57% in all cases. The sulfide production was supported with acetate-butyrate, being the former commonly accumulated because of the oxidation of higher organic compounds; in this case, its utilization sustained sulfate reduction. This process could be controlled by parameters such as HRT and sulfate loading rate to improve the performance of the bioreactor in the treatment of the effluents contaminated with metals in a two-stage system.The present work aimed to evaluate the production of sulfide through the application of different hydraulic retention times (HRT) and different sulfate loading rates in an up-flow anaerobic sludge blanket (UASB) reactor utilizing acetate-butyrate as electron donors and the coupling of the reactor to a crystallizer to remove metals. The sulfidogenic sludge for the UASB was generated from hydrothermal vent sediments and this was operated at room temperature (18-22 ºC). The sulfate reduction process was linked to the precipitation of Cu2+, Zn2+ and Al3+ in a crystallizer coupled to the UASB reactor (two-stage system) to avoid the toxicity of the metals to the sludge. The concentration of dissolved sulfide increased with the HRT up to 312.9 mg HS–/L at 3 d of HRT. As the sulfate loading rate was increasing, the maximum sulfide concentration obtained was of 376.8 mg HS–/L at 500 mg SO4–2/L/d (1500 mg/L), whereas the concentration of Cu2+, Zn2+ and Al3+ was up to 150, 100, and 100 mg/L, respectively. The removal efficiencies of Cu2+, Zn2+, and Al3+ were higher than 98% when they were fed separately. When a mixture of metals was added, the removal efficiency was close to 80%. Recovery of metals was lower than 57% in all cases. The sulfide production was supported with acetate-butyrate, being the former commonly accumulated because of the oxidation of higher organic compounds; in this case, its utilization sustained sulfate reduction. This process could be controlled by parameters such as HRT and sulfate loading rate to improve the performance of the bioreactor in the treatment of the effluents contaminated with metals in a two-stage system
Vanadio: exposición atmosférica, efectos en la salud y normatividad en México: Revisión de la literatura
No full textAir pollution is a major global problem. Among the most important environmental pollutants is particulate matter, which has been classified by the International Agency for Research on Cancer as a human carcinogen within Group 1. Toxicologically relevant components such as metals are added to suspended particulate matter, which is at least partly responsible for the adverse effects of particulate matter on organisms. One of the metals present in particulate matter is vanadium, which is found as an abundant trace element in Mexican petroleum and is emitted into the atmosphere mainly by burning its derivatives, such as gasoline. However, although vanadium is present in the atmosphere, its concentrations are not monitored since neither vanadium nor any other metal are considered criteria pollutants. Therefore, the objective of this work is to give visibility to this element as a ubiquitous pollutant attached to suspended particles, which represents a potential danger to the health of the inhabitants of polluted cities such as the Metropolitan Zone of the Valley of Mexico; and, on the other hand, to emphasize the near absence of regulations in Mexico on metal pollution, since vanadium is only one example.La contaminación atmosférica es uno de los grandes problemas a nivel global. Dentro de los contaminantes ambientales más importantes están las partículas suspendidas, las cuales han sido clasificadas dentro del Grupo 1 como carcinógenas para humanos por la Agencia Internacional sobre la Investigación en Cáncer. A las partículas suspendidas se adosan componentes con relevancia toxicológica como los metales a los que se les atribuyen, al menos en parte, los efectos adversos que las partículas generan en los organismos. Uno de los metales presentes en las partículas es el vanadio, metal que se encuentra como elemento traza abundante en el petróleo mexicano y que se emite a la atmósfera principalmente por la quema de sus derivados, como la gasolina. Sin embargo, aunque el vanadio está presente en la atmósfera, sus concentraciones no se monitorean, ya que ni éste ni algún otro metal están considerados como contaminantes criterio. Por lo anterior, el objetivo de este trabajo es darle visibilidad a este elemento como contaminante ubicuo adosado a las partículas suspendidas, ya que representa un potencial peligro para la salud de los habitantes de las ciudades contaminadas como la Zona Metropolitana del Valle de México y, por otro lado, enfatizar la casi nula de normatividad en México sobre la contaminación por metales, ya que el vanadio es solo un ejemplo de ésta
Fitotoxicidad y fitorremediación de un suelo contaminado con gasolina utilizando plantas de girasol asistidas por bacterias rizosféricas nativas
Get PDFPhytoremediation is an alternative for cleaning contaminated soils using plants and associative microorganisms. This study evaluated the phytotoxicity and phytoremediation of a gasoline-contaminated soil by sunflower plants (Helianthus annuus L.) assisted with native rhizosphere bacteria. The research consisted of three experimental phases based on artificially gasoline-contaminated soil. The first phase evaluated the seed germination and seedling emergence under contaminated soil (0, 200, 400, 800, 1600, 2400, and 3200 mg/kg); for 20 days, seed germination and seedling tolerance were achieved at all concentrations. The second phase of the study isolated bacteria from the contaminated soil, characterized by biochemical tests related to plant growth promotion, and molecularly identified. Gasoline inhibited bacterial growth, and ten potential plant growth-promoting bacteria were isolated, which belonged to Bacillus, Streptomyces, Pseudomonas, Priestia, Massilia, and Sphingobium. The third phase consisted of a bioassay for phytoremediation of gasoline-contaminated soil (0, 1600, and 3200 mg/kg) by inoculating sunflower plants with the ten bacteria obtained from phase 2 as a bacterial consortium. After 60 days, despite not having influenced plant growth, bacterial inoculation significantly diminished the soil contaminant (~50 % removal). The inoculation of the sunflower plants with ten native bacteria reduced the gasoline-contamination in soil.La fitorremediación es una alternativa para limpiar suelos contaminados utilizando plantas y sus microorganismos asociados. El presente trabajo evaluó la fitotoxicidad y la fitorremediación de un suelo contaminado con gasolina por plantas de girasol (Helianthus annuus L.) asistida con bacterias rizosféricas nativas. Esta investigación contempló tres fases experimentales partiendo de un suelo artificialmente contaminado con gasolina. La primera fase evaluó la germinación de semillas de girasol y su crecimiento en un suelo contaminado (0, 200, 400, 800, 1600, 2400 y 3200 mg/kg), observándose la germinación y la tolerancia de las plántulas en todas las concentraciones de gasolina, a los 20 días. En la segunda fase se aislaron bacterias totales del suelo contaminado y se caracterizaron mediante pruebas bioquímicas relacionadas con el crecimiento vegetal y se identificaron molecularmente. La gasolina inhibió el crecimiento bacteriano, y se seleccionaron 10 cepas con capacidad promotora del crecimiento vegetal, sobresaliendo los géneros Bacillus, Streptomyces, Pseudomonas, Priestia, Massilia y Sphingobium. La tercera fase consistió en un bioensayo de fitorremediación del suelo contaminado (0, 1600 y 3200 mg/kg) inoculando plantas con las 10 bacterias aisladas de la fase 2, aplicadas en consorcio. A los 60 días, a pesar de no influir en el crecimiento vegetal, las bacterias disminuyeron significativamente la presencia del contaminante en el suelo (~50 % remoción). La inoculación de girasol con bacterias nativas es una alternativa para reducir la contaminación de gasolina en el suelo
Acid mine drainage neutralization rate using biogenic calcite
Get PDFIn this study, the chicken eggshell (ES) particle size was evaluated in relation to the neutralization rate (γ) of acid mine drainage (AMD) under stirring conditions. Four treatments were carried out using three different particle sizes (<63, 250−500, and 1,410−2,000 μm). In the treatments T1−T3, the pH increase (ΔpH) was monitored every 5 min and ES was added until a pH ~6.0 was reached and the γ was calculated every 5 min. In T4, ΔpH and γ were measured every 8 hours for 48 hours, and ES particle size <63 μm was used. At the end of each treatment, the redox potential (Eh), SO42– removal efficiency (ηSO42–), and heavy metal (HM) removal efficiency (ηHM) were determined. The γ values to achieve a pH ~6.0 were 1.6×10−1, 1.1×10−1 y 6.0×10−2 min–1 for particle size of <63, 250−500, and 1410-2000 μm, respectively. However, regardless of particle size, the highest γ effect was observed within the first 5−10 min. Overall, the Eh was reduced to ca. 210 mV in all treatments. The maximum ηSO42– was ca. 70% in T1 and T4. However, the larger the particle size, the longer and higher ES concentration was needed to achieve a pH ~6.0 and the ηSO42– was lower. The maximum ηHM recorded in all treatments were 100% for Al, Fe, and Mo. The use of ES with particle size <63 μm reduced the concentration needed to reach the target pH, increased the γ, favored the ηSO42–, and removed the Fe3+ decreasing the Eh.In this study, the chicken eggshell (ES) particle size was evaluated in relation to the neutralization rate (γ) of acid mine drainage (AMD) under stirring conditions. Four treatments were carried out using three different particle sizes (<63, 250−500, and 1,410−2,000 μm). In the treatments T1−T3, the pH increase (ΔpH) was monitored every 5 min and ES was added until a pH ~6.0 was reached and the γ was calculated every 5 min. In T4, ΔpH and γ were measured every 8 hours for 48 hours, and ES particle size <63 μm was used. At the end of each treatment, the redox potential (Eh), SO42– removal efficiency (ηSO42–), and heavy metal (HM) removal efficiency (ηHM) were determined. The γ values to achieve a pH ~6.0 were 1.6×10−1, 1.1×10−1 y 6.0×10−2 min–1 for particle size of <63, 250−500, and 1410-2000 μm, respectively. However, regardless of particle size, the highest γ effect was observed within the first 5−10 min. Overall, the Eh was reduced to ca. 210 mV in all treatments. The maximum ηSO42– was ca. 70% in T1 and T4. However, the larger the particle size, the longer and higher ES concentration was needed to achieve a pH ~6.0 and the ηSO42– was lower. The maximum ηHM recorded in all treatments were 100% for Al, Fe, and Mo. The use of ES with particle size <63 μm reduced the concentration needed to reach the target pH, increased the γ, favored the ηSO42–, and removed the Fe3+ decreasing the Eh
Estudio experimental del uso de residuos de botellas de plástico en el hormigón convencional
Get PDFImproper management of plastic bottle waste is harming the environment. Recycling this waste for inclusion in the concrete matrix is a viable alternative for its final disposal. The objective of this study was to evaluate the mechanical behavior of conventional concrete with the addition of polyethylene terephthalate (PET) fibers, designed according to the procedures established by the American Concrete Institute for a strength of 20 MPa. The analyzed properties of the concrete included consistency, density, compressive strength, and flexural strength. Sixty cylindrical and 60 prismatic specimens with PET fiber additions of 0%, 2%, 4%, 6%, and 8% by weight of cement were prepared for testing at 7, 14, and 28 days of curing. The results indicate that maximum compressive and flexural strengths of 22.79 MPa and 3.19 MPa are achieved at 28 days by adding 2% and 6% PET fibers. Therefore, its application is recommended up to a proportion of 4%, where the corresponding dosage is 15.78 kilograms of PET fibers per cubic meter of concrete with a workable consistency.Improper management of plastic bottle waste is harming the environment. Recycling this waste for inclusion in the concrete matrix is a viable alternative for its final disposal. The objective of this study was to evaluate the mechanical behavior of conventional concrete with the addition of polyethylene terephthalate (PET) fibers, designed according to the procedures established by the American Concrete Institute for a strength of 20 MPa. The analyzed properties of the concrete included consistency, density, compressive strength, and flexural strength. Sixty cylindrical and 60 prismatic specimens with PET fiber additions of 0%, 2%, 4%, 6%, and 8% by weight of cement were prepared for testing at 7, 14, and 28 days of curing. The results indicate that maximum compressive and flexural strengths of 22.79 MPa and 3.19 MPa are achieved at 28 days by adding 2% and 6% PET fibers. Therefore, its application is recommended up to a proportion of 4%, where the corresponding dosage is 15.78 kilograms of PET fibers per cubic meter of concrete with a workable consistency
Electro-phytoremediation of polluted soil at pilot level using maize (Fabricio Espejel and Reyna García, Editors)
No full textThis article presents the imposition of a direct current electric field in the presence of seeds and plants of Zea mays L., to rehabilitate soils contaminated with hydrocarbons at a pilot level, and its influence on some physical and chemical properties of the soil, such as pH, electrical conductivity, organic matter content in the soil, enzymatic activity, bulk density, apparent density, porosity, cation exchange capacity, and soluble cations such as potassium, sodium, and calcium. For this reason, the edaphological characterization was carried out before and after an electro-phytoremediation process of soils contaminated with hydrocarbons, using an IrO2-Ta2O5|Ti anode and a titanium cathode, applying a constant electric field of 0.2 V/cm for 4 h to maize seeds and stimulating their germination. After one week, an electric field of 0.1 V/cm for 8 h was applied to the maize seeds every day for 42 days to stimulate the growth of maize plants. This study demonstrated the removal of hydrocarbons by electro-phytoremediation. The applied electric field increases seed germination and plant growth of Zea mays L. These results were obtained with the different transport phenomena that develop when using the electric field in the soil Vertisol pelic understudy at a pilot level.This article presents the imposition of a direct current electric field in the presence of seeds and plants of Zea mays L., to rehabilitate soils contaminated with hydrocarbons at a pilot level, and its influence on some physical and chemical properties of the soil, such as pH, electrical conductivity, organic matter content in the soil, enzymatic activity, bulk density, apparent density, porosity, cation exchange capacity, and soluble cations such as potassium, sodium, and calcium. For this reason, the edaphological characterization was carried out before and after an electro-phytoremediation process of soils contaminated with hydrocarbons, using an IrO2-Ta2O5|Ti anode and a titanium cathode, applying a constant electric field of 0.2 V/cm for 4 h to maize seeds and stimulating their germination. After one week, an electric field of 0.1 V/cm for 8 h was applied to the maize seeds every day for 42 days to stimulate the growth of maize plants. This study demonstrated the removal of hydrocarbons by electro-phytoremediation. The applied electric field increases seed germination and plant growth of Zea mays L. These results were obtained with the different transport phenomena that develop when using the electric field in the soil Vertisol pelic understudy at a pilot level
Potencial del arbusto Lantana camara L. (Verbenaceae) para la fitoestabilización y volatilización de mercurio
Get PDFMercury (Hg) is the most harmful heavy metal for living beings due to its high toxicity, persistence and bioaugmentation in the food web. L. camara has been considered as a promising plant for the phytoremediation of different metals, but its response to Hg has not been characterized. The objective of this study was to evaluate the effectiveness of L. camara to bioaccumulate, transfer and volatilize Hg, in artificially contaminated soils (1.0 and 8.0 mg/kg of Hg). After two months of treatment, the dry weight was measured, and the Hg present in stems, roots, leaves and atmosphere was quantified by means of atomic absorption spectroscopy. Volatilized Hg was captured in hermetic chambers with continuous air flow, connected to a trap solution (5 % KMnO4 dissolved in H2SO4). The translocation factor was <1 and the bioaccumulation factor was >10 in both treatments. High mercury volatilized Hgº values in soil solution indicate that approximately 7.1 µg/g plant/day can be released into the atmosphere. Our results indicate that L. camara accumulates Hg mainly in the root, showing potential for phytostabilization; but its high volatilization rates point towards a more restricted use of this species in phytoremediation strategies.Mercury (Hg) is the most harmful heavy metal for living beings due to its high toxicity, persistence, and bioaugmentation in the food web. Lantana camara has been considered promising for the phytoremediation of different metals, but its response to Hg has not been characterized. The objective of this study was to evaluate the effectiveness of L. camara to bioaccumulate, translocate, and volatilize Hg in artificially contaminated soils (1.0 and 8.0 mg/kg Hg). After two months of treatment, the dry weight was measured and the Hg present in stems, roots, leaves, and atmosphere was quantified using atomic absorption spectroscopy. The volatilized Hg was captured in hermetic chambers with continuous airflow, connected to a trap solution (5 % KMnO4 dissolved in H2SO4). The translocation factor was < 1, and the bioaccumulation factor was > 1 in both treatments. The Hgº values volatilized in high mercury indicate that approximately 7.1 µg/g plant/day can be released into the atmosphere. Our results indicate that L. camara accumulates Hg mainly in the root, showing potential for phytostabilization, but the observed volatilization rates point towards a more restricted use of this species in phytoremediation strategies
Cyanotoxins bioaccumulation by fish in an anthropized reservoir in central Mexico
Get PDFThe bioaccumulation of cyanotoxins has been well documented in exposed organisms including fish, which represent a potential route to cyanotoxins transfer to humans by consumption of contaminated food. We determined the bioaccumulation of neurotoxic saxitoxins and hepatotoxic microcystins in muscle and liver/viscera of native (Goodea atripinnis), introduced (Poeciliopsis gracilis), and commercially important (Oreochromis niloticus) fish in Santa Catarina, an anthropized reservoir in Central Mexico. Additionally, we calculated the potential risk of human exposure due to the consumption of the studied species. The Santa Catarina Reservoir showed some physical and chemical water parameters generally associated with cyanobacterial blooms (e.g., high phycocyanin, chlorophyll-a, dissolved phosphorus concentrations, and alkaline pH) with presence of cyanotoxins produced by the cyanobacteria genera Microcystis, Dolichospermum, and Planktothrix, which were found in dissolved and particulate (sestonic) fractions of water. Moreover, we detected the presence of saxitoxins and microcystins in the tissues of all species studied. The risk of intoxication for humans was lower for the consumption of Nile tilapia muscle than for the other analyzed species, whose consumption should be avoided since it exceeds the recommended daily intake of microcystins for a short-term (i.e., two-week exposure time). These findings are remarkable because commercial fishing in reservoirs and the consumption of these fish could represent a route to human exposure to toxins, particularly microcystins. Our results highlight the need for the detection of cyanotoxins and the evaluation of their bioaccumulation by fish in unstudied eutrophic waterbodies, to reduce the potential health risk for humans and the environment.The bioaccumulation of cyanotoxins has been well documented in exposed organisms including fish, which represent a potential route to cyanotoxins transfer to humans by consumption of contaminated food. We determined the bioaccumulation of neurotoxic saxitoxins and hepatotoxic microcystins in muscle and liver/viscera of native (Goodea atripinnis), introduced (Poeciliopsis gracilis), and commercially important (Oreochromis niloticus) fish in Santa Catarina, an anthropized reservoir in Central Mexico. Additionally, we calculated the potential risk of human exposure due to the consumption of the studied species. The Santa Catarina Reservoir showed some physical and chemical water parameters generally associated with cyanobacterial blooms (e.g., high phycocyanin, chlorophyll-a, dissolved phosphorus concentrations, and alkaline pH) with presence of cyanotoxins produced by the cyanobacteria genera Microcystis, Dolichospermum, and Planktothrix, which were found in dissolved and particulate (sestonic) fractions of water. Moreover, we detected the presence of saxitoxins and microcystins in the tissues of all species studied. The risk of intoxication for humans was lower for the consumption of Nile tilapia muscle than for the other analyzed species, whose consumption should be avoided since it exceeds the recommended daily intake of microcystins for a short-term (i.e., two-week exposure time). These findings are remarkable because commercial fishing in reservoirs and the consumption of these fish could represent a route to human exposure to toxins, particularly microcystins. Our results highlight the need for the detection of cyanotoxins and the evaluation of their bioaccumulation by fish in unstudied eutrophic waterbodies, to reduce the potential health risk for humans and the environment
Análisis de la NOM-083-SEMARNAT-2003 y su proyecto de modificación 2021 bajo categorías de sostenibilidad. aplicación a tres sitios de disposición final
Get PDFThe Official Gazette of the Federation in México published on May 10, 2021 the “NOM-083-SEMARNAT-2003 Modification Project” (Project-083-SEMARNAT-2021), for the correct disposal of municipal solid waste and special management, which considers the updating of technologies and commitments to climate change. The objective of this work was to analyze NOM-083-SEMARNAT-2003 and its Project-083-SEMARNAT-2021, as well as evaluate under their criteria three final disposal sites (FDS), to determine the areas of opportunity and the challenges involved in complying with the proposed modifications under the sustainability approach. To this end, comparative tables were prepared, the criteria were classified into social, environmental, technical and economic categories and compared with Royal Decree 646/2020 of Spain. The evaluation of the FDS with both Mexican regulations, was carried out using verification tables. In Project-083-SEMARNAT-2021, 44 criteria were included, the classification of FDS and the requirements for type D were modified. The NOM-083-SEMARNAT-2003 and the Project-083-SEMARNAT-2021 prioritize environmental category (53% and 47%, respectively) and the social category is 10% lower than the Spanish regulations. Compliance with the Project-083-SEMARNAT-2021 was lower by 1.6%, 2.6% and 8.3% for the FDS of Tenango del Valle, Aculco and Xalatlaco, State of Mexico respectively. The results confirm that the Project-083-SEMARNAT-2021 requirements are more rigorous and although they imply a greater investment, their implementation will reduce the environmental and social impact, which will contribute to the signed commitments of the 2030 Agenda.El Diario Oficial de la Federación en México publicó el 10 de mayo de 2021 el “Proyecto de Modificación de la NOM-083-SEMARNAT-2003” (Proyecto-083-SEMARNAT-2021), para la correcta disposición de los residuos sólidos urbanos y de manejo especial, que considera la actualización de tecnologías y los compromisos ante el cambio climático. El objetivo del presente trabajo fue analizar la NOM-083-SEMARNAT-2003 y su Proyecto-083-SEMARNAT-2021, así como evaluar bajo sus criterios tres sitios de disposición final (SDF), para determinar las áreas de oportunidad y los retos que implica el cumplimiento de las modificaciones propuestas bajo el enfoque de la sostenibilidad. Para ello se elaboraron cuadros comparativos, se clasificaron los criterios en las categorías social, ambiental, técnico y económico y, se compararon con el Real Decreto 646/2020 de España. La evaluación de los SDF con ambas normas Mexicanas, se realizó utilizando tablas de verificación. En el Proyecto-083-SEMARNAT-2021 se incluyeron 44 criterios, se modificó la clasificación de los SDF y los requerimientos para el tipo D. La NOM-083-SEMARNAT-2003 y el Proyecto-083-SEMARNAT-2021 priorizan la categoría ambiental (53 % y 47%, respectivamente) y la categoría social es 10 % menor que la normatividad española. El cumplimiento con el Proyecto-083-SEMARNAT-2021 fue menor en 1.6 %, 2.6 % y 8.3 % para los SDF de Tenango del Valle, Aculco y Xalatlaco, Estado de México respectivamente. Los resultados ratifican que los requerimientos del Proyecto-083-SEMARNAT-2021 son más riguroso y aunque implican mayor inversión, su implementación disminuirá el impacto ambiental y social, lo cual contribuirá a los compromisos signados de la Agenda 2030